ISSCC 2006 Circuit Design Forum 4

San Francisco, Feb. 9, 2006
1-hour session of Forum F4
(An abstract for the complete Forum is available.)

Color Coding

Digital camera systems obviously deliver digital image data - however, there is a wide variety of digital image standards to which that data can be encoded. In this talk, we will review the technical parameters of digital image exchange standards. We will introduce nonlinear coding ("gamma correction"), and discuss how optoelectronic transfer functions (OETFs) are optimized for the characteristics of vision and for the characteristics of sensing and reproduction devices. We will review the choice of white reference and primary chromaticities. We will detail the parameters of the sRGB, the de facto color image exchange standard used in consumer imaging.

Image encoding standards (including sRGB) involve assumptions about the conditions of image reproduction - that is, assumptions about the viewing environment. For example, artificial increases in both color saturation and contrast are required to achieve acceptable image quality when an image is acquired in a bright environment and reproduced in a dim environment, compared to colorimetrically accurate reproduction. We will discuss the necessary transforms. We will review the relevant technical characteristics of modern displays and printers, and discuss how techniques such as color management can transform and optimize image data for particular devices.

The sRGB standard can reproduce only a moderate range of colors - sRGB has a moderate "color gamut" - and it is limited to a modest contrast ratio. We will introduce the technologies of wide-gamut and high dynamic range (HDR) imaging, using as examples systems currently deplyed in high-end computer graphics, HDTV, and digital cinema.

Presenter:

Charles Poynton is an independent contractor specializing in the physics, mathematics, and engineering of digital color imaging systems, including digital video, HDTV, and digital cinema (D‑cinema). While at Sun Microsystems, from 1988 to 1995, he initiated Sun's HDTV research project, and introduced color management technology to Sun. Soon after its introduction in February 2003, Mr. Poynton's book, Digital Video and HDTV Algorithms and Interfaces, was Amazon.com's 3,339-th most popular book.

Charles Poynton - Courses & seminars
2006-04-08